add mzGetStoredEntry function

mzGetStoredEntry gives you a pointer and address to the data of a zip
entry, assuming that entry is stored rather than deflated.

Change-Id: Ifb39777c98d1d50475ef7de419cf28935f5f9965
diff --git a/minzip/Zip.h b/minzip/Zip.h
index 05a2e60..2054b38 100644
--- a/minzip/Zip.h
+++ b/minzip/Zip.h
@@ -183,6 +183,17 @@
     const ZipEntry *pEntry, unsigned char* buffer);
 
 /*
+ * Return a pointer and length for a given entry.  The returned region
+ * should be valid until pArchive is closed, and should be treated as
+ * read-only.
+ *
+ * Only makes sense for entries which are stored (ie, not compressed).
+ * No guarantees are made regarding alignment of the returned pointer.
+ */
+bool mzGetStoredEntry(const ZipArchive *pArchive,
+    const ZipEntry* pEntry, unsigned char **addr, size_t *length);
+
+/*
  * Inflate all entries under zipDir to the directory specified by
  * targetDir, which must exist and be a writable directory.
  *